Arthroscopic devices and methods

ABSTRACT

An electrosurgical probe can be detachably secured to a handpiece having a motor drive unit and an RF current contact. The electrosurgical probe includes an elongate shaft having a longitudinal axis, a distal dielectric tip, and a proximal hub which is detachably securable to the handpiece. A hook electrode is reciprocatably mounted in the distal dielectric tip, and an RF connector on the hub is couplable to the RF current contact in the handpiece when the hub is secured to the handpiece. A drive mechanism in the hub mechanically couples to the hook electrode, and drive mechanism engages a rotational component in the motor drive unit when the hub is secured to the handpiece. The drive mechanism converts rotational motion from the rotational component into axial reciprocation and transmits the axial reciprocation to the hook electrode to axially displace the hook electrode between a non-extended position and an extended position relative to the dielectric tip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional application No.62/306,516 (Attorney Docket No. 41879-715.101), filed on Mar. 10, 2016,provisional application No. 62/309,324 (Attorney Docket No.41879-719.101), filed on Mar. 16, 2016, and provisional application No.62/325,025 (Attorney Docket No. 41879-719.102), filed on Apr. 20, 2016,the full disclosures of which are incorporated herein by reference.

The disclosure of the present application is related to that ofapplication Ser. No. 15/421,264 (Attorney Docket No. 41879-714.201),filed on Jan. 31, 2017, the full disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to arthroscopic tissue cutting and ablationdevices by which anatomical tissues may be resected, ablated and removedfrom a joint or other site. More specifically, this invention relates toelectrosurgical probes and methods for ablating and removing softtissue.

In many arthroscopic procedures including subacromial decompression,anterior cruciate ligament reconstruction, and resection of theacromioclavicular joint, there is a need for cutting and removing andsoft tissue. Currently, surgeons use arthroscopic shavers havingrotational cutting surfaces to remove soft tissue in such procedures.

The need exists for arthroscopic instrument that remove soft tissuerapidly. Recently, arthroscopic surgical cutters capable of selectivelyremoving both hard tissues and soft tissues have been developed. Suchcutters are described in the following US Patent Publications which arecommonly assigned with the present application: US20130253498;US20160113706; US20160346036 US20160157916; and US20160081737, the fulldisclosures of which are incorporated herein by reference.

While very effective, it would be desirable to provide arthroscopicsurgical cutters and cutter systems as “reposable” devices withdisposable cutting components and reusable, sterilizable handles.Preferably, the handles would incorporate as many of the high valuesystem components as possible. Further preferably, the handle designswould have a minimum number of external connections to simplifysterilization and set-up. Still more preferably, the cutters and systemswould allow for bipolar cutting as well as monopolar and mechanical(cutting blade) resection. In particular, it would be desirable toprovide arthroscopic cutters having non-rotational cutters, such asaxially reciprocating cutters and RF cutting wires, and cutters that canalso operate in an ablation mode. At least some of these objectives willbe met by the inventions described herein.

2. Description of the Background Art

U.S. Pat. No. 6,149,620 and U.S. Pat. No. 7,678,069 describe tools forthe volumetric removal of soft tissue in the knee and elsewhere.Co-pending, commonly owned U.S. patent application Ser. No. 15/421,264(Attorney Docket No. 41879-714.201), filed on Jan. 31, 2017, describes atissue removal device which can remove tissue by cutting (resection)and/or by radiofrequency (RF) ablation. US 2008/0188848 describes anelectrosurgical cutter with a handpiece and a removable cutterinstrument. Other commonly assigned published US Patent Applicationshave been listed above, including US20130253498; US20160113706;US20160346036; US20160157916; and US20160081737.

SUMMARY OF THE INVENTION

The present invention provides apparatus such as electrosurgical probes.In exemplary embodiments, an electrosurgical probe comprises anelongated shaft assembly having a proximal end, a distal end, and alongitudinal axis. A distal housing is mounted on the distal end of theshaft and in one embodiment has a laterally open window, that is, aplane of the window is generally perpendicular to the longitudinal axisof the shaft. An interior channel extends axially through the shaft andextends through an interior of the housing to a window in the housing.An electrode member with an elongated edge which may be serrated extendslongitudinally across the window and is configured to reciprocate theelongated edge longitudinally relative to the window.

In specific embodiments, the shaft may comprise an outer sleeve and aninner sleeve, and the distal housing may be a ceramic and is mounted ona distal end of the outer sleeve. The electrode member is mounted on adistal end of the inner sleeve, and the inner sleeve may bereciprocatably mounted in the outer sleeve. A proximal hub is attachedto a proximal end of the outer sleeve and a sliding collar is coupled toa proximal end of the inner sleeve, the sliding collar being mounted andconfigured to axially reciprocate within the proximal hub while beingrestrained from rotation relative to the proximal hub. In particularexamples, a rotating drive coupling is mounted to rotate in the proximalhub while being restrained from axially translating relative to theproximal hub. The rotating drive coupling can have a distal surfacewhich engages a proximal surface on the sliding collar, and the distaland proximal surfaces may have cam surfaces or otherwise shaped so thatrotation and/or rotational oscillation of the rotating coupling causesthe sliding collar to axially reciprocate within the proximal hub whichin turn will cause the elongate edge of the electrode member to axiallyreciprocate relative to the window in the distal housing.

While the dimensions and geometries of the probe are usually notcritical, in specific designs, the electrode member may reciprocate witha stroke in a range from 0.01 mm and 10 mm, often being in a rangebetween 0.1 mm and 5 mm. The elongate edge may be substantially flushwith the circumference of the distance housing. Further, the electrodeedges may be configured to extend over edges or the window duringreciprocation.

The electrosurgical probes of the present invention may further comprisea handpiece and motor drive operatively coupled to the shaft andconfigured to axially reciprocate the electrode at high speed relativeto the window to provide a method of dynamic ablation. Usually, aproximal hub is connected to the proximal end of the elongated shaft,and the handpiece and motor drive are detachably coupled to the proximalhub. A negative pressure source is provided for coupling through thehandpiece and proximal hub to an interior channel of the shaft whichcommunicates with the window in the distal housing. The motor drive istypically configured to axially reciprocate the electrode edge at a ratein a range from 1 Hz and 1,000 Hz.

The distal housing or tip is a ceramic and may have a variety ofspecific geometries, and in one embodiment is attached to the distal endof the shaft. The ceramic tip has an opening therein that typicallydefines a circular or flower-shaped window that communicates with aninterior channel in the tip and the shaft. In specific embodiments, thereciprocating component carries an electrode member that has a L-shapedor hook geometry with an axial region extending through ceramic tip andis coupled to an elongate member disposed in the shaft and configuredfor reciprocation through the opening. The ceramic tip or housing may bemounted on a distal end of the outer sleeve and the hook electrode maybe mounted or crimped to the distal end of the elongate member which isreciprocatably mounted in the outer

In a broad aspect, the present invention provides a method for ablatingand/or resecting, cutting or slicing tissue. The method comprisesengaging an electrode protruding from the housing against a surface ofthe tissue. An elongate edge of an electrode member may be reciprocatedlongitudinally to the window in a plane perpendicular to the plane ofthe window, and a radiofrequency current with a cutting waveform may beapplied to the electrode member to dynamically ablate tissue andgenerate tissue debris. A vacuum may be applied to the interior channelin the housing to aspirate the tissue debris through window.

In some embodiments, the elongate edge of the electrode member mayprotrude beyond the plane of the housing, while in other embodiments theedge may be flushed with or recessed into the housing circumference. Theelectrode member is typically reciprocated at a rate in a range from 1Hz and 1,000 Hz, usually between 1 Hz and 500 Hz.

In a first specific aspect, the present invention provides anelectrosurgical probe for use with a handpiece having a motor drive unitand a radiofrequency (RF) current contact. The probe comprises anelongate shaft having a longitudinal axis, a distal dielectric tip, anda proximal hub configured to be detachably secured to the handpiece. AnRF hook electrode may be reciprocatably mounted on or in the distaldielectric tip of the elongate shaft, and an RF connector on the hub isconfigured to couple to the RF current contact in the handpiece when thehub is secured to the handpiece. The hub of the probe further includes adrive mechanism which is mechanically coupled to the hook electrode. Thedrive mechanism is configured to engage a rotational component which ispart of the motor drive unit when the hub is secured to the handpiece.Typically, the rotational component will be a rotating spindle of thetype commonly found on electric motors, where the spindle drives orincludes a mechanical coupler configured to releasably or detachablyengage and mechanically couple to the drive mechanism of the probe. Thedrive mechanism in the hub of the probe is configured to convertrotational motion from the rotational component of the handpiece intoaxial reciprocation or translation (e.g., being a rotating cam assembly)and to transmit the axial reciprocation or translation to the hookelectrode, resulting in axial displacement or shifting of the hookelectrode between a non-extended position and an extended positionrelative to the dielectric tip of the elongate shaft.

In exemplary embodiments, the drive mechanism comprises a rod, tube, orother elongate member disposed in, on, or through the elongate shaft andhas a distal end attached to the hook electrode. The drive mechanismincludes a device or assembly, such as a rotatable cam assembly, locatedin the hub to receive rotational motion from the spindle or otherrotational component of the motor drive unit. The cam or other assemblyconverts the rotational motion into axial reciprocation which isdelivered to the elongate member and subsequently transmitted throughthe shaft.

In further exemplary embodiments of the electrosurgical probe, theelongate member may be electrically conductive and connected to deliverRF current from the RF connector in the hub to the RF electrode. Forexample, the elongate member may be an electrically conductive metal rodor tube which extends the entire length of the elongate shaft to providean electrically conductive path from the RF connector on the hub to thehook electrode. In particular embodiments, a proximal portion of theelongate member extends through a central opening in the hub and anintermediate portion of the elongate member extends through a centrallumen in the shaft. The hook electrode is then reciprocatably disposedin an opening in the dielectric tip. Typically, the central lumen in theshaft is configured to be connected to a negative pressure (vacuum orsuction) source, and the hub is configured to connect the central lumento the negative pressure source.

In more specific exemplary embodiments, the shaft comprises an outertube having a longitudinal lumen and an inner member reciprocatablyreceived in the longitudinal lumen of the outer tube. The distaldielectric tip is typically attached to a distal end of the outer tubeand will have an opening which is contiguous with the longitudinal lumenof the outer tube. The hook electrode is attached to a distal end of theinner member so that the electrode can reciprocate within the innermember relative to the outer tube.

In some embodiments, the inner member may comprise a rod, and the hookelectrode may comprise a bent wire attached to a distal end of the rod.In such cases, the longitudinal lumen of the outer member is configuredto be connected to a negative pressure source. Often, a distal face ofthe dielectric distal tip may have a recess and a notch so that alateral end of the bent wire of the hook electrode can be retracted intothe recess and notch when the hook electrode is in its non-extendedposition.

In still further exemplary embodiments, the shaft may have at least oneinterior channel, and the dielectric distal tip may have at least oneflow channel. Usually, the at least one interior channel and at leastone flow channel are contiguous and configured to be connected to anegative pressure source to provide a continuous suction or vacuum paththerethrough. Usually, at least one flow channel will have across-sectional area of at least 0.001 in². The cross-sectional area ofthe at least one flow channel is typically configured to accommodatefluid outflows of at least 50 ml/min when the at least one interiorchannel and the at least one flow channel are connected to the negativepressure source. In certain embodiments, the at least one flow channelcomprises a portion of an opening in the dielectric distal tip whichreceives the hook electrode. In other embodiments, the distal electrictip may have at least one opening to receive the hook electrode and inadditional have one flow channel.

In still further exemplary embodiments, the distal electrode tipincludes at least one opening to receive the hook electrode. The atleast one opening which receives the hook electrode is usually (i)shaped with a plurality of support elements adapted or configured tosupport elongate member and/or (ii) includes a plurality of flowchannels adapted or configured to provide fluid flow in response tosuction from the negative pressure source. In such embodiments, therewill typically be at least three support elements, sometimes being fouror more support elements, and the dielectric tip typically comprises aceramic material.

In a second specific aspect, the present invention provides anelectrosurgical system comprising an electrosurgical probe and ahandpiece configured to be detachably connected to the electrosurgicalprobe. The electrosurgical probe may have any of the configurations,components, and designs described previously and elsewhere herein. Thehandpiece will be configured to detachably connect to the hub on theelectrosurgical probe, and the handpiece will include a motor drive unitwhich is configured to mechanically couple to the drive mechanism of theelectrosurgical probe in order to longitudinally reciprocate theelongate member and hook electrode between non-extended positions andextended positions when the hub is secured to the handpiece.

In exemplary embodiments, the systems of the present invention mayfurther comprise a controller configured to activate and de-activate(energize and de-energize), the motor drive unit in order to shift theelongate member and hook electrode between the non-extended position andthe extended position relative to the dielectric trip. Usually, thecontroller will be further configured to deliver RF current to theelectrode. The RF current may be delivered only when the electrode is inits extended position or may be delivered only when it's in theretracted condition, or still further at all times while the electrodeis being reciprocated. The RF current may have a waveform selected forany known surgical purpose, for example cutting wave forms, coagulationwave forms, and the like.

In still further specific embodiments, the controller may be configuredto longitudinally reciprocate the elongate member while simultaneouslydelivering RF current to the hook electrode. In other embodiments, thehook electrode may be further optionally configured to rotate orrotationally oscillate the hook electrode, either with or without thesimultaneous delivery of RF current. More usually, however, the hookelectrodes will be axially reciprocated with no rotational and/oroscillational motion.

The drive mechanism, motor drive unit, controller, and other componentsof the systems in the present invention may be configured to reciprocatethe hook electrode over a distance in the range from 0.01 mm to 5 mm,usually between 0.1 mm and 4 mm. The controller and motor drive unit maybe further configured to reciprocate the hook electrode at a rate in therange from 5 Hz to 500 Hz, usually at a rate in the range from 10 Hz to100 Hz.

In a third specific aspect, the present invention provides methods forassembling an electrosurgical probe system. The methods compriseproviding a first electrosurgical probe, providing a handpiece, andremovably attaching a hub on the first electrosurgical probe to thehandpiece. Attaching the hub to the probe causes mechanical attachmentof a motor drive unit in the handpiece to a drive mechanism in theelectrosurgical probe. The drive mechanism in the probe longitudinallyreciprocates the elongate member in the probe to in turn reciprocate anRF electrode located at a distal end of the elongate member between anon-extended position and an extended position.

Removably attaching the hub on the electrosurgical probe to the firsthandpiece will usually also couple or otherwise connect an RF connectoron the hub to the RF current contact on the first handpiece. Theassembly methods may further comprise detaching the firstelectrosurgical probe from the handpiece after the electrosurgical probesystem has been used to treat a patient. In some cases, after the firstelectrosurgical probe has been removed, the hub on a second differentprobe can then be removably attached to the handpiece and used to treatthe patient.

In a fourth aspect, the present invention provides a method forelectrosurgically resecting tissue. The method comprises positioning adistal tip of a shaft having a longitudinal axis at a tissue targetsite. By placing the distal tip of the shaft adjacent to the targettissue and rotating a motor in the handpiece, the hook electrode can beaxially reciprocated at the distal tip of the shaft. The hook electrodetypically is shifted between an axially non-extended or partiallyextended position and an axially extended position relative to thedielectric tip. By engaging the hook electrode against the targettissue, and delivering RF current through the hook electrode to thetarget tissue engaged by the electrode, the tissue may be resected,ablated, coagulated, or the like.

In some specific embodiments, the motor is driven only enough to movethe hook electrode to a stationary position, typically either a fullyextended position or a fully retracted position. Alternatively, themotor and handpiece may be run continuously in order to effect tissueresection as the RF electrode acts as a cutting blade when the probe isadvanced through tissue. In all cases, a negative pressure will usuallybe drawn through an interior lumen of the shaft to aspirate a regionaround the target tissue where the resection, ablation, or the like isbeing effected.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It should be appreciated that thedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting in scope.

FIG. 1 is a perspective view of a disposable arthroscopic cutter or burrassembly with a ceramic cutting member carried at the distal end of arotatable inner sleeve with a window in the cutting member proximal tothe cutting edges of the burr.

FIG. 2 is an enlarged perspective view of the ceramic cutting member ofthe arthroscopic cutter or burr assembly of FIG. 1.

FIG. 3 is a perspective view of a handle body with a motor drive unit towhich the burr assembly of FIG. 1 can be coupled, with the handle bodyincluding an LCD screen for displaying operating parameters of deviceduring use together with a joystick and mode control actuators on thehandle.

FIG. 4 is an enlarged perspective view of the ceramic cutting membershowing a manner of coupling the cutter to a distal end of the innersleeve of the burr assembly.

FIG. 5A is a cross-sectional taken along line 5A-5A of FIG. 2 showingthe close tolerance between sharp cutting edges of a window in a ceramiccutting member and sharp lateral edges of the outer sleeve whichprovides a scissor-like cutting effect in soft tissue.

FIG. 5B is a cross-sectional view similar to FIG. 5A with the ceramiccutting member in a different rotational position than in FIG. 5A.

FIG. 6 is a perspective view of another ceramic cutting member carriedat the distal end of an inner sleeve with a somewhat rounded distal noseand deeper flutes than the cutting member of FIGS. 2 and 4, and withaspiration openings or ports formed in the flutes.

FIG. 7 is a perspective view of another ceramic cutting member withcutting edges that extend around a distal nose of the cutter togetherwith an aspiration window in the shaft portion and aspiration openingsin the flutes.

FIG. 8 is a perspective view of a ceramic housing carried at the distalend of the outer sleeve.

FIG. 9 is a perspective of another variation of a ceramic member withcutting edges that includes an aspiration window and an electrodearrangement positioned distal to the window.

FIG. 10 is an elevational view of a ceramic member and shaft of FIG. 9showing the width and position of the electrode arrangement in relationto the window.

FIG. 11 is an end view of the ceramic member of FIGS. 9-10 the outwardperiphery of the electrode arrangement in relation to the rotationalperiphery of the cutting edges of the ceramic member.

FIG. 12A is a schematic view of the working end and ceramic cuttingmember of FIGS. 9-11 illustrating a step in a method of use.

FIG. 12B is another view of the working end of FIG. 12A illustrating asubsequent step in a method of use to ablate a tissue surface.

FIG. 12C is a view of the working end of FIG. 12A illustrating a methodof tissue resection and aspiration of tissue chips to rapidly removevolumes of tissue.

FIG. 13A is an elevational view of an alternative ceramic member andshaft similar to that of FIG. 9 illustrating an electrode variation.

FIG. 13B is an elevational view of another ceramic member similar tothat of FIG. 12A illustrating another electrode variation.

FIG. 13C is an elevational view of another ceramic member similar tothat of FIGS. 12A-12B illustrating another electrode variation.

FIG. 14 is a perspective view of an alternative working end and ceramiccutting member with an electrode partly encircling a distal portion ofan aspiration window.

FIG. 15A is an elevational view of a working end variation with anelectrode arrangement partly encircling a distal end of the aspirationwindow.

FIG. 15B is an elevational view of another working end variation with anelectrode positioned adjacent a distal end of the aspiration window.

FIG. 16 is a perspective view of a variation of a working end andceramic member with an electrode adjacent a distal end of an aspirationwindow having a sharp lateral edge for cutting tissue.

FIG. 17 is a perspective view of a variation of a working end andceramic member with four cutting edges and an electrode adjacent adistal end of an aspiration window.

FIG. 18 is a perspective view of a variation of another type ofelectrosurgical ablation device that can be detachably coupled to ahandpiece as shown in FIG. 23.

FIG. 19A is a perspective view of the working end and ceramic housing ofthe device of FIG. 18 showing an electrode in a first position relativeto a side-facing window.

FIG. 19B is a perspective view of the working end of FIG. 19A showingthe electrode in a second position relative to the window.

FIG. 20A is a sectional view of the working end and electrode of FIG.19A.

FIG. 20B is a sectional view of the working end and electrode of FIG.19B.

FIG. 21A is a sectional view of the hub of the probe of FIG. 18 takenalong line 21A-21A of FIG. 18 showing an actuation mechanism in a firstposition.

FIG. 21B is a sectional view of the hub of FIG. 21A showing theactuation mechanism in a second position.

FIG. 22 is a sectional view of the hub of FIG. 21A rotated 90° toillustrate electrical contacts and pathways in the hub.

FIG. 23 is a schematic diagram of as RF system that includes acontroller console, handpiece with a motor drive and a footswitch.

FIG. 24 is a perspective view of the RF probe of FIG. 18 from adifferent angle showing the drive coupling.

FIG. 25 is a perspective view is a perspective view of a variation ofanother type of electrosurgical ablation device that can be detachablycoupled to a handpiece as shown in FIG. 23, which has a hook typeelectrode that is moveable with a motor drive.

FIG. 26A is a perspective view of the working end of the probe FIG. 25with the hook electrode in a non-extended position relative to adielectric distal tip.

FIG. 26B is a view of the working end of FIG. 26A with the hookelectrode in an extended position.

FIG. 27 is a sectional view of the working end of FIG. 26B with the hookelectrode in an extended position.

FIG. 28 is a sectional view of the dielectric tip of FIGS. 26A-27 withthe hook electrode removed to show the fluid flow channels therein.

FIG. 29 is an end view of an alternative dielectric tip similar to thatof FIGS. 26A-28 with a different configuration of fluid flow channelstherein.

FIG. 30 is an end view of another dielectric tip with a differentconfiguration of fluid flow channels.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to devices for cutting, ablating andremoving bone and soft tissue and related methods of use. Severalvariations of the invention will now be described to provide an overallunderstanding of the principles of the form, function and methods of useof the devices disclosed herein. In one variation, the presentdisclosure provides for an arthroscopic cutter or burr assembly forcutting or abrading bone that is disposable and is configured fordetachable coupling to a non-disposable handle and motor drivecomponent. This description of the general principles of this inventionis not meant to limit the inventive concepts in the appended claims.

In general, one embodiment provides a high-speed rotating ceramic cutteror burr that is configured for use in many arthroscopic surgicalapplications, including but not limited to treating bone in shoulders,knees, hips, wrists, ankles and the spine. More in particular, thedevice includes a cutting member that is fabricated entirely of aceramic material that is extremely hard and durable, as described indetail below. A motor drive is operatively coupled to the ceramic cutterto rotate the burr edges at speeds ranging from 3,000 RPM to 20,000 RPM.

In one variation shown in FIGS. 1-2, an arthroscopic cutter or burrassembly 100 is provided for cutting and removing hard tissue, whichoperates in a manner similar to commercially available metals shaversand burrs. FIG. 1 shows disposable burr assembly 100 that is adapted fordetachable coupling to a handle 104 and motor drive unit 105 therein asshown in FIG. 3.

The cutter assembly 100 has a shaft 110 extending along longitudinalaxis 115 that comprises an outer sleeve 120 and an inner sleeve 122rotatably disposed therein with the inner sleeve 122 carrying a distalceramic cutting member 125. The shaft 110 extends from a proximal hubassembly 128 wherein the outer sleeve 120 is coupled in a fixed mannerto an outer hub 140A which can be an injection molded plastic, forexample, with the outer sleeve 120 insert molded therein. The innersleeve 122 is coupled to an inner hub 140B (phantom view) that isconfigured for coupling to the motor drive unit 105 (FIG. 3). The outerand inner sleeves 120 ands 122 typically can be a thin wall stainlesssteel tube, but other materials can be used such as ceramics, metals,plastics or combinations thereof.

Referring to FIG. 2, the outer sleeve 120 extends to distal sleeveregion 142 that has an open end and cut-out 144 that is adapted toexpose a window 145 in the ceramic cutting member 125 during a portionof the inner sleeve's rotation. Referring to FIGS. 1 and 3, the proximalhub 128 of the burr assembly 100 is configured with a J-lock, snap-fitfeature, screw thread or other suitable feature for detachably lockingthe hub assembly 128 into the handle 104. As can be seen in FIG. 1, theouter hub 140A includes a projecting key 146 that is adapted to matewith a receiving J-lock slot 148 in the handle 104 (see FIG. 3).

In FIG. 3, it can be seen that the handle 104 is operatively coupled byelectrical cable 152 to a controller 155 which controls the motor driveunit 105. Actuator buttons 156 a, 156 b or 156 c on the handle 104 canbe used to select operating modes, such as various rotational modes forthe ceramic cutting member. In one variation, a joystick 158 may bemoved forward and backward to adjust the rotational speed of the ceramiccutting member 125. The rotational speed of the cutter can continuouslyadjustable, or can be adjusted in increments up to 20,000 RPM. FIG. 3further shows that negative pressure source 160 is coupled to aspirationtubing 162 which communicates with a flow channel in the handle 104 andlumen 165 in inner sleeve 122 which extends to window 145 in the ceramiccutting member 125 (FIG. 2).

Now referring to FIGS. 2 and 4, the cutting member 125 comprises aceramic body or monolith that is fabricated entirely of a technicalceramic material that has a very high hardness rating and a highfracture toughness rating, where “hardness” is measured on a Vickersscale and “fracture toughness” is measured in MPam^(1/2). Fracturetoughness refers to a property which describes the ability of a materialcontaining a flaw or crack to resist further fracture and expresses amaterial's resistance to brittle fracture. The occurrence of flaws isnot completely avoidable in the fabrication and processing of anycomponents.

The authors evaluated technical ceramic materials and tested prototypesto determine which ceramics are best suited for the non-metal cuttingmember 125. When comparing the material hardness of the ceramic cuttersof the invention to prior art metal cutters, it can easily be understoodwhy typical stainless steel bone burrs are not optimal. Types 304 and316 stainless steel have hardness ratings of 1.7 and 2.1, respectively,which is low and a fracture toughness ratings of 228 and 278,respectively, which is very high. Human bone has a hardness rating of0.8, so a stainless steel cutter is only about 2.5 times harder thanbone. The high fracture toughness of stainless steel provides ductilebehavior which results in rapid cleaving and wear on sharp edges of astainless steel cutting member. In contrast, technical ceramic materialshave a hardness ranging from approximately 10 to 15, which is five tosix times greater than stainless steel and which is 10 to 15 timesharder than cortical bone. As a result, the sharp cutting edges of aceramic remain sharp and will not become dull when cutting bone. Thefracture toughness of suitable ceramics ranges from about 5 to 13 whichis sufficient to prevent any fracturing or chipping of the ceramiccutting edges. The authors determined that a hardness-to-fracturetoughness ratio (“hardness-toughness ratio”) is a useful term forcharacterizing ceramic materials that are suitable for the invention ascan be understood form the Chart A below, which lists hardness andfracture toughness of cortical bone, a 304 stainless steel, and severaltechnical ceramic materials.

CHART A Hard- Fracture Ratio Hard- ness Toughness ness to Frac- (GPa)(MPam^(1/2)) ture Toughness Cortical bone 0.8 12  .07:1 Stainless steel304 2.1 228  .01:1 Yttria-stabilized zirconia (YTZP) YTZP 2000 12.5 101.25:1 (Superior Technical Ceramics) YTZP 4000 12.5 10 1.25:1 (SuperiorTechnical Ceramics) YTZP (CoorsTek) 13.0 13 1.00:1 Magnesia stabilizedzirconia (MSZ) Dura-Z ® 12.0 11 1.09:1 (Superior Technical Ceramics) MSZ200 (CoorsTek) 11.7 12 0.98:1 Zirconia toughened alumina (ZTA) YTA-1414.0 5 2.80:1 (Superior Technical Ceramics) ZTA (CoorsTek) 14.8 6 2.47:1Ceria stabilized zirconia CSZ (Superior Technical Ceramics) 11.7 120.98:1 Silicon Nitride SiN (Superior Technical Ceramics) 15.0 6 2.50:1

As can be seen in Chart A, the hardness-toughness ratio for the listedceramic materials ranges from 98× to 250× greater than thehardness-toughness ratio for stainless steel 304. In one aspect of theinvention, a ceramic cutter for cutting hard tissue is provided that hasa hardness-toughness ratio of at least 0.5:1, 0.8:1 or 1:1.

In one variation, the ceramic cutting member 125 is a form of zirconia.Zirconia-based ceramics have been widely used in dentistry and suchmaterials were derived from structural ceramics used in aerospace andmilitary armor. Such ceramics were modified to meet the additionalrequirements of biocompatibility and are doped with stabilizers toachieve high strength and fracture toughness. The types of ceramics usedin the current invention have been used in dental implants, andtechnical details of such zirconia-based ceramics can be found inVolpato, et al., “Application of Zirconia in Dentistry: Biological,Mechanical and Optical Considerations”, Chapter 17 in Advances inCeramics—Electric and Magnetic Ceramics, Bioceramics, Ceramics andEnvironment (2011).

In one variation, the ceramic cutting member 125 is fabricated of anyttria-stabilized zirconia as is known in the field of technicalceramics, and can be provided by CoorsTek Inc., 16000 Table MountainPkwy., Golden, Colo. 80403 or Superior Technical Ceramics Corp., 600Industrial Park Rd., St. Albans City, Vt. 05478. Other technicalceramics that may be used consist of magnesia-stabilized zirconia,ceria-stabilized zirconia, zirconia toughened alumina and siliconnitride. In general, in one aspect of the invention, the monolithicceramic cutting member 125 has a hardness rating of at least 8 Gpa(kg/mm²). In another aspect of the invention, the ceramic cutting member125 has a fracture toughness of at least 2 MPam^(1/2).

The fabrication of such ceramics or monoblock components are known inthe art of technical ceramics, but have not been used in the field ofarthroscopic or endoscopic cutting or resecting devices. Ceramic partfabrication includes molding, sintering and then heating the molded partat high temperatures over precise time intervals to transform acompressed ceramic powder into a ceramic monoblock which can provide thehardness range and fracture toughness range as described above. In onevariation, the molded ceramic member part can have additionalstrengthening through hot isostatic pressing of the part. Following theceramic fabrication process, a subsequent grinding process optionallymay be used to sharpen the cutting edges 175 of the burr (see FIGS. 2and 4).

In FIG. 4, it can be seen that in one variation, the proximal shaftportion 176 of cutting member 125 includes projecting elements 177 whichare engaged by receiving openings 178 in a stainless steel split collar180 shown in phantom view. The split collar 180 can be attached aroundthe shaft portion 176 and projecting elements 177 and then laser weldedalong weld line 182. Thereafter, proximal end 184 of collar 180 can belaser welded to the distal end 186 of stainless steel inner sleeve 122to mechanically couple the ceramic body 125 to the metal inner sleeve122. In another aspect of the invention, the ceramic material isselected to have a coefficient of thermal expansion between is less than10 (1×10⁶/° C.) which can be close enough to the coefficient of thermalexpansion of the metal sleeve 122 so that thermal stresses will bereduced in the mechanical coupling of the ceramic member 125 and sleeve122 as just described. In another variation, a ceramic cutting membercan be coupled to metal sleeve 122 by brazing, adhesives, threads or acombination thereof.

Referring to FIGS. 1 and 4, the ceramic cutting member 125 has window145 therein which can extend over a radial angle of about 10° to 90° ofthe cutting member's shaft. In the variation of FIG. 1, the window ispositioned proximally to the cutting edges 175, but in other variations,one or more windows or openings can be provided and such openings canextend in the flutes 190 (see FIG. 6) intermediate the cutting edges 175or around a rounded distal nose of the ceramic cutting member 125. Thelength L of window 145 can range from 2 mm to 10 mm depending on thediameter and design of the ceramic member 125, with a width W of 1 mm to10 mm.

FIGS. 1 and 4 shows the ceramic burr or cutting member 125 with aplurality of sharp cutting edges 175 which can extend helically,axially, longitudinally or in a cross-hatched configuration around thecutting member, or any combination thereof. The number of cutting edges175 ands intermediate flutes 190 can range from 2 to 100 with a flutedepth ranging from 0.10 mm to 2.5 mm. In the variation shown in FIGS. 2and 4, the outer surface or periphery of the cutting edges 175 iscylindrical, but such a surface or periphery can be angled relative toaxis 115 or rounded as shown in FIGS. 6 and 7. The axial length AL ofthe cutting edges can range between 1 mm and 10 mm. While the cuttingedges 175 as depicted in FIG. 4 are configured for optimal bone cuttingor abrading in a single direction of rotation, it should be appreciatedthe that the controller 155 and motor drive 105 can be adapted to rotatethe ceramic cutting member 125 in either rotational direction, oroscillate the cutting member back and forth in opposing rotationaldirections.

FIGS. 5A-5B illustrate a sectional view of the window 145 and shaftportion 176 of a ceramic cutting member 125′ that is very similar to theceramic member 125 of FIGS. 2 and 4. In this variation, the ceramiccutting member has window 145 with one or both lateral sides configuredwith sharp cutting edges 202 a and 202 b which are adapted to resecttissue when rotated or oscillated within close proximity, or inscissor-like contact with, the lateral edges 204 a and 204 b of thesleeve walls in the cut-out portion 144 of the distal end of outersleeve 120 (see FIG. 2). Thus, in general, the sharp edges of window 145can function as a cutter or shaver for resecting soft tissue rather thanhard tissue or bone. In this variation, there is effectively no open gapG between the sharp edges 202 a and 202 b of the ceramic cutting member125′ and the sharp lateral edges 204 a, 204 b of the sleeve 120. Inanother variation, the gap G between the window cutting edges 202 a, 202b and the sleeve edges 204 a, 204 b is less than about 0.020″, or lessthan 0.010″.

FIG. 6 illustrates another variation of ceramic cutting member 225coupled to an inner sleeve 122 in phantom view. The ceramic cuttingmember again has a plurality of sharp cutting edges 175 and flutes 190therebetween. The outer sleeve 120 and its distal opening and cut-outshape 144 are also shown in phantom view. In this variation, a pluralityof windows or opening 245 are formed within the flutes 190 andcommunicate with the interior aspiration channel 165 in the ceramicmember as described previously.

FIG. 7 illustrates another variation of ceramic cutting member 250coupled to an inner sleeve 122 (phantom view) with the outer sleeve notshown. The ceramic cutting member 250 is very similar to the ceramiccutter 125 of FIGS. 1, 2 and 4, and again has a plurality of sharpcutting edges 175 and flutes 190 therebetween. In this variation, aplurality of windows or opening 255 are formed in the flutes 190intermediate the cutting edges 175 and another window 145 is provided ina shaft portion 176 of ceramic member 225 as described previously. Theopenings 255 and window 145 communicate with the interior aspirationchannel 165 in the ceramic member as described above.

It can be understood that the ceramic cutting members can eliminate thepossibility of leaving metal particles in a treatment site. In oneaspect of the invention, a method of preventing foreign particle inducedinflammation in a bone treatment site comprises providing a rotatablecutter fabricated of a ceramic material having a hardness of at least 8Gpa (kg/mm²) and/or a fracture toughness of at least 2 MPam^(1/2) androtating the cutter to cut bone without leaving any foreign particles inthe treatment site. The method includes removing the cut bone tissuefrom the treatment site through an aspiration channel in a cuttingassembly.

FIG. 8 illustrates variation of an outer sleeve assembly with therotating ceramic cutter and inner sleeve not shown. In the previousvariations, such as in FIGS. 1, 2 and 6, shaft portion 176 of theceramic cutter 125 rotates in a metal outer sleeve 120. FIG. 8illustrates another variation in which a ceramic cutter (not shown)would rotate in a ceramic housing 280. In this variation, the shaft or aceramic cutter would thus rotate is a similar ceramic body which may beadvantageous when operating a ceramic cutter at high rotational speeds.As can be seen in FIG. 8, a metal distal metal housing 282 is welded tothe outer sleeve 120 along weld line 288. The distal metal housing 282is shaped to support and provide strength to the inner ceramic housing282.

FIGS. 9-11 are views of an alternative tissue resecting assembly orworking end 400 that includes a ceramic member 405 with cutting edges410 in a form similar to that described previously. FIG. 9 illustratesthe monolithic ceramic member 405 carried as a distal tip of a shaft orinner sleeve 412 as described in previous embodiments. The ceramicmember 405 again has a window 415 that communicates with aspirationchannel 420 in shaft 412 that is connected to negative pressure source160 as described previously. The inner sleeve 412 is operatively coupledto a motor drive 105 and rotates in an outer sleeve 422 of the typeshown in FIG. 2. The outer sleeve 422 is shown in FIG. 10.

In the variation illustrated in FIG. 9, the ceramic member 405 carriesan electrode arrangement 425, or active electrode, having a singlepolarity that is operatively connected to an RF source 440. A returnelectrode, or second polarity electrode 430, is provided on the outersleeve 422 as shown in FIG. 10. In one variation, the outer sleeve 422can comprise an electrically conductive material such as stainless steelto thereby function as return electrode 445, with a distal portion ofouter sleeve 422 is optionally covered by a thin insulative layer 448such as parylene, to space apart the active electrode 425 from thereturn electrode 430.

The active electrode arrangement 425 can consist of a single conductivemetal element or a plurality of metal elements as shown in FIGS. 9 and10. In one variation shown in FIG. 9, the plurality of electrodeelements 450 a, 450 b and 450 c extend transverse to the longitudinalaxis 115 of ceramic member 405 and inner sleeve 412 and are slightlyspaced apart in the ceramic member. In one variation shown in FIGS. 9and 10, the active electrode 425 is spaced distance D from the distaledge 452 of window 415 which is less than 5 mm and often less than 2 mmfor reasons described below. The width W and length L of window 415 canbe the same as described in a previous embodiment with reference to FIG.4.

As can be seen in FIGS. 9 and 11, the electrode arrangement 425 iscarried intermediate the cutting edges 410 of the ceramic member 405 ina flattened region 454 where the cutting edges 410 have been removed. Ascan be best understood from FIG. 11, the outer periphery 455 of activeelectrode 425 is within the cylindrical or rotational periphery of thecutting edges 410 when they rotate. In FIG. 11, the rotational peripheryof the cutting edges is indicated at 460. The purpose of the electrode'souter periphery 455 being equal to, or inward from, the cutting edgeperiphery 460 during rotation is to allow the cutting edges 410 torotate at high RPMs to engage and cut bone or other hard tissue withoutthe surface or the electrode 425 contacting the targeted tissue.

FIG. 9 further illustrates a method of fabricating the ceramic member405 with the electrode arrangement 425 carried therein. The moldedceramic member 405 is fabricated with slots 462 that receive theelectrode elements 450 a-450 c, with the electrode elements fabricatedfrom stainless steel, tungsten or a similar conductive material. Eachelectrode element 450 a-450 c has a bore 464 extending therethrough forreceiving an elongated wire electrode element 465. As can be seen inFIG. 9, and the elongated wire electrode 465 can be inserted from thedistal end of the ceramic member 405 through a channel in the ceramicmember 405 and through the bores 464 in the electrode elements 450 a-450c. The wire electrode 465 can extend through the shaft 412 and iscoupled to the RF source 440. The wire electrode element 465 thus can beused as a means of mechanically locking the electrode elements 450 a-450c in slots 462 and also as a means to deliver RF energy to the electrode425.

Another aspect of the invention is illustrated in FIGS. 9-10 wherein itcan be seen that the electrode arrangement 425 has a transversedimension TD relative to axis 115 that is substantial in comparison tothe window width W as depicted in FIG. 10. In one variation, theelectrode's transverse dimension TD is at least 50% of the window widthW, or the transverse dimension TD is at least 80% of the window width W.In the variation of FIGS. 9-10, the electrode transverse dimension TD is100% or more of the window width W. It has been found that tissue debrisand byproducts from RF ablation are better captured and extracted by awindow 415 that is wide when compared to the width of the RF plasmaablation being performed.

In general, the tissue resecting system comprises an elongated shaftwith a distal tip comprising a ceramic member, a window in the ceramicmember connected to an interior channel in the shaft and an electrodearrangement in the ceramic member positioned distal to the window andhaving a width that is at 50% of the width of the window, at 80% of thewidth of the window or at 100% of the width of the window. Further, thesystem includes a negative pressure source 160 in communication with theinterior channel 420.

Now turning to FIGS. 12A-12C, a method of use of the resecting assembly400 of FIG. 9 can be explained. In FIG. 12A, the system and a controlleris operated to stop rotation of the ceramic member 405 in a selectedposition were the window 415 is exposed in the cut-out 482 of the openend of outer sleeve 422 shown in phantom view. In one variation, acontroller algorithm can be adapted to stop the rotation of the ceramic405 that uses a Hall sensor 484 a in the handle 104 (see FIG. 3) thatsenses the rotation of a magnet 484 b carried by inner sleeve hub 140Bas shown in FIG. 2. The controller algorithm can receive signals fromthe Hall sensor which indicated the rotational position of the innersleeve 412 and ceramic member relative to the outer sleeve 422. Themagnet 484 b can be positioned in the hub 140B (FIG. 2) so that whensensed by the Hall sensor, the controller algorithm can de-activate themotor drive 105 so as to stop the rotation of the inner sleeve in theselected position.

Under endoscopic vision, referring to FIG. 12B, the physician then canposition the electrode arrangement 425 in contact with tissue targeted Tfor ablation and removal in a working space filled with fluid 486, suchas a saline solution which enables RF plasma creation about theelectrode. The negative pressure source 160 is activated prior to orcontemporaneously with the step of delivering RF energy to electrode425. Still referring to FIG. 12B, when the ceramic member 405 ispositioned in contact with tissue and translated in the direction ofarrow Z, the negative pressure source 160 suctions the targeted tissueinto the window 415. At the same time, RF energy delivered to electrodearrangement 425 creates a plasma P as is known in the art to therebyablate tissue. The ablation then will be very close to the window 415 sothat tissue debris, fragments, detritus and byproducts will be aspiratedalong with fluid 486 through the window 415 and outwardly through theinterior extraction channel 420 to a collection reservoir. In one methodshown schematically in FIG. 12B, a light movement or translation ofelectrode arrangement 425 over the targeted tissue will ablate a surfacelayer of the tissue and aspirate away the tissue detritus.

FIG. 12C schematically illustrates a variation of a method which is ofparticular interest. It has been found if suitable downward pressure onthe working end 400 is provided, then axial translation of working end400 in the direction arrow Z in FIG. 12C, together with suitablenegative pressure and the RF energy delivery will cause the plasma P toundercut the targeted tissue along line L that is suctioned into window415 and then cut and scoop out a tissue chips indicated at 488. Ineffect, the working end 400 then can function more as a high volumetissue resecting device instead of, or in addition to, its ability tofunction as a surface ablation tool. In this method, the cutting orscooping of such tissue chips 488 would allow the chips to be entrainedin outflows of fluid 486 and aspirated through the extraction channel420. It has been found that this system with an outer shaft diameter of7.5 mm, can perform a method of the invention can ablate, resect andremove tissue greater than 15 grams/min, greater than 20 grams/min, andgreater than 25 grams/min.

In general, a method corresponding to the invention includes providingan elongated shaft with a working end 400 comprising an active electrode425 carried adjacent to a window 415 that opens to an interior channelin the shaft which is connected to a negative pressure source,positioning the active electrode and window in contact with targetedtissue in a fluid-filled space, activating the negative pressure sourceto thereby suction targeted tissue into the window and delivering RFenergy to the active electrode to ablate tissue while translating theworking end across the targeted tissue. The method further comprisesaspirating tissue debris through the interior channel 420. In a method,the working end 400 is translated to remove a surface portion of thetargeted tissue. In a variation of the method, the working end 400 istranslated to undercut the targeted tissue to thereby remove chips 488of tissue.

Now turning to FIGS. 13A-13C, other distal ceramic tips of cuttingassemblies are illustrated that are similar to that of FIGS. 9-11,except the electrode configurations carried by the ceramic members 405are varied. In FIG. 13A, the electrode 490A comprises one or moreelectrode elements extending generally axially distally from the window415. FIG. 13B illustrates an electrode 490B that comprises a pluralityof wire-like elements 492 projecting outwardly from surface 454. FIG.13C shows electrode 490C that comprises a ring-like element that ispartly recessed in a groove 494 in the ceramic body. All of thesevariations can produce an RF plasma that is effective for surfaceablation of tissue, and are positioned adjacent to window 415 to allowaspiration of tissue detritus from the site.

FIG. 14 illustrates another variation of a distal ceramic tip 500 of aninner sleeve 512 that is similar to that of FIG. 9 except that thewindow 515 has a distal portion 518 that extends distally between thecutting edges 520, which is useful for aspirating tissue debris cut byhigh speed rotation of the cutting edges 520. Further, in the variationof FIG. 14, the electrode 525 encircles a distal portion 518 of window515 which may be useful for removing tissue debris that is ablated bythe electrode when the ceramic tip 500 is not rotated but translatedover the targeted tissue as described above in relation to FIG. 12B. Inanother variation, a distal tip 500 as shown in FIG. 14 can be energizedfor RF ablation at the same time that the motor drive rotates back andforth (or oscillates) the ceramic member 500 in a radial arc rangingfrom 1° to 180° and more often from 10° to 90°.

FIGS. 15A-15B illustrate other distal ceramic tips 540 and 540′ that aresimilar to that of FIG. 14 except the electrode configurations differ.In FIG. 15A, the window 515 has a distal portion 518 that again extendsdistally between the cutting edges 520, with electrode 530 comprising aplurality of projecting electrode elements that extend partly around thewindow 515. FIG. 15B shows a ceramic tip 540′ with window 515 having adistal portion 518 that again extends distally between the cutting edges520. In this variation, the electrode 545 comprises a single bladeelement that extends transverse to axis 115 and is in close proximity tothe distal end 548 of window 515.

FIG. 16 illustrates another variation of distal ceramic tip 550 of aninner sleeve 552 that is configured without the sharp cutting edges 410of the embodiment of FIGS. 9-11. In other respects, the arrangement ofthe window 555 and the electrode 560 is the same as describedpreviously. Further, the outer periphery of the electrode is similar tothe outward surface of the ceramic tip 550. In the variation of FIG. 16,the window 555 has at least one sharp edge 565 for cutting soft tissuewhen the assembly is rotated at a suitable speed from 500 to 5,000 RPM.When the ceramic tip member 550 is maintained in a stationary positionand translated over targeted tissue, the electrode 560 can be used toablate surface layers of tissue as described above.

FIG. 17 depicts another variation of distal ceramic tip 580 coupled toan inner sleeve 582 that again has sharp burr edges or cutting edges 590as in the embodiment of FIGS. 9-11. In this variation, the ceramicmonolith has only 4 sharp edges 590 which has been found to work wellfor cutting bone at high RPMs, for example from 8,000 RPM to 20,000 RPM.In this variation, the arrangement of window 595 and electrode 600 isthe same as described previously. Again, the outer periphery ofelectrode 595 is similar to the outward surface of the cutting edges590.

FIGS. 18-24 illustrate another electrosurgical RF ablation device orprobe 700 (FIG. 18) that is adapted for use with a handpiece 702 andmotor drive unit 105 (see FIG. 23). In FIG. 23, the console 704 carriesRF source 705A and a negative pressure source or outflow pump 705B whichcan comprise a peristaltic pump and cassette to provide suction thoughtubing 706 coupled to the handpiece 702 as is known in the art. Theconsole 704 further can carry a controller 705C that operates the motordrive as well as actuation and/or modulation of the RF source 705A andnegative pressure source 705B. A footswitch 707 a is provided foroperation of RF source 705A, negative pressure source 705B andoptionally the motor drive. In addition, the motor drive 105, RF sourceand negative pressure source can be operated by control buttons 707 b inthe handpiece 702 (FIG. 23). In the RF probe of FIGS. 18 to 22, themotor drive 105 does not rotate a cutting blade or electrode but insteadmoves or reciprocates an RF electrode axially at a selectedreciprocation rate (which may be a high or low reciprocation rate or asingle reciprocation) to dynamically ablate, resect and remove tissue.

More in particular, referring to FIG. 18, the detachable RF ablationprobe 700 has a proximal housing portion or hub 708 that is coupled toan elongated shaft or extension portion 710 that has an outer diameterranging from about 2 mm to 7 mm, and in one variation is from 5 mm to 6mm in diameter. The shaft 710 extends about longitudinal axis 712 to aworking end including a housing or body 715 that comprises a dielectricmaterial such as a ceramic as described above, referred to hereinbelowas ceramic housing 715. Referring to FIGS. 18, 19A-19B and 20A-20B, itcan be seen that elongated shaft 710 comprises an outer sleeve 716 andan inner sleeve 718. Both sleeves 716 and 718 may comprise a thin wallstainless steel tube or another similar material or composite that iselectrically conductive. The outer sleeve 716 has a distal end 719 thatis coupled to the ceramic housing 715. An interior channel 720 extendsthrough the housing 715 to a distal channel opening 722 in housing 715.In this variation or embodiment, the channel opening 722 in part facessideways or laterally in the housing 715 relative to axis 712 and alsofaces in the distal direction. That is, the distal opening 722 extendsover both distal and lateral faces of the ceramic housing 715.

Referring to FIGS. 19A-19B, a moveable active electrode 725 isconfigured to extend laterally across a window 726 which has a planarsurface and is a section of opening 722 in housing 715. As can be seenin FIGS. 20A-20B, the electrode 725 is carried at the distal end ofreciprocating inner sleeve 718. The electrode 725 is adapted to bedriven by motor drive unit 105 in handpiece 702 (see FIG. 23) so thatproximal-facing edge 728 a and side-facing edges 728 b of electrode 725move axially relative to the window 726. FIG. 19A and the correspondingsectional view of FIG. 20A show the inner sleeve 718 and electrode 725moved by motor drive 105 to an extended or distal axial positionrelative to window 726. FIGS. 19B and 20B show the inner sleeve 718 andelectrode 725 moved by the motor drive to a non-extended or retractedposition relative to window 726. In FIGS. 19A and 20A, the window 726has an open window length WL that can be defined as the dimensionbetween the proximal window edge 730 and the proximal-facing electrodeedge 728. The moving electrode 725 moves through a stroke between adistally extended position (FIGS. 19A and 20A) and a distally retractedposition (FIGS. 19B and 20B) wherein the electrode edge 728 a in theretracted position (FIGS. 19B and 20B) is adapted to extend over theproximal window edge 730 to shear tissue and clean the electrodesurface. Likewise, referring to FIGS. 19A-19B, the side-facing edges 728b of electrode 725 extend over the lateral edges 731 of window 726 toshear tissue engaged by suction in the window.

As can be seen in FIGS. 20A-20B, the inner sleeve 718 comprises athin-wall tube of stainless steel or another conductive material, and iscoupled to RF source 705A (FIG. 23) to carry RF current to the electrode725. The inner sleeve 718 has a distal end 732 that coupled by a weld toa conductive metal rod or element 734 that extends transversely througha dielectric body 735 carried by the inner sleeve. The conductiveelement 734 is welded to electrode 725 that extends laterally across thewindow 726. The dielectric body 735 can be a ceramic, polymer orcombination thereof and is in part configured to provide an insulatorlayer around to electrical conductive components (inner sleeve 718 andtransverse rod 734) to define the “active electrode” as the limitedsurface area of electrode 725 which enhances RF energy delivery to theelectrode edges 728 a and 728 b for tissue cutting. The inner sleeve 718also has side-facing window 736 therein that cooperates or aligns withwindow 726 in housing 715 to provide suction through the windows 736 and726 from negative pressure source 705B (see FIGS. 20A and 23) to drawtissue into the window 726.

Now turning to FIGS. 18, 21A-21B, 22 and 23, the mechanism that axiallytranslates the electrode 725 in window 726 is described in more detail.As can be understood from FIGS. 18, 21A and 23, the RF ablation probe700 can be locked into handpiece 702 of FIG. 22 by inserting tabs 737 aand 737 b on flex arms 738 a and 738 b (FIGS. 18 and 21A) into receivingopenings 740 a and 740 b in handpiece 702 (FIG. 23). O-rings 742 a and742 b are provided in hub 708 (FIG. 21A-21B) to seal the hub 708 intothe receiving channel 741 in the handpiece 702 (FIG. 23).

Referring now to FIGS. 21A-21B, the hub 708 is fixed to outer sleeve 716that has a bore or channel 720 therein in which the inner sleeve 718 isslidably disposed. A proximal end 744 of inner sleeve 718 has anactuator collar 745 of an electrically conductive material attachedthereto with a proximal-facing surface 746 that has a bump or camsurface 747 thereon. The actuator collar 745 is adapted to reciprocatewithin bore 748 in the hub 708. FIG. 21A shows the actuator collar 745in an extended position which corresponds to the extended electrodeposition of FIGS. 19A and 20A. FIG. 21B shows the actuator collar 745 ina non-extended or retracted position which corresponds to the retractedelectrode position of FIGS. 19B and 20B.

The actuator collar 745 and hub 708 include slot and key featuresdescribed further below to allow for axial reciprocation of the slidingactuator collar 745 and inner sleeve 718 while preventing rotation ofthe collar 745 and sleeve 718. A spring 748 between a distal surface 750of actuator collar 745 and a proximally facing internal surface 752 ofhub 708 urges the sliding actuator collar 745 and the moveable activeelectrode 725 toward the retracted or proximal-most position as shown inFIGS. 19B, 20B and 21B.

The motor drive 105 of handpiece 702 (FIG. 23) couples to a rotatingdrive coupling 760 fabricated of a non-conductive material that rotatesin hub 708 as shown in FIGS. 18 and 21A-21B. The drive coupling 760 hasa distal cam surface 762 that engages the proximal-facing cam surface747 on the actuator collar 745 so that rotation of drive coupling 760will reciprocate the sliding actuator collar 745 through a forward andbackward stroke AA, as schematically shown in FIGS. 21A-21B. While thecam surfaces 762 and 747 are illustrated schematically as bumps or cams,one of skill in the art will appreciate that the surfaces can beundulating or “wavy” or alternately comprise multiple facets to providea ratchet-like mechanism wherein rotation of the rotating drive couplingin 360° will reciprocate the sliding actuator collar 745 through aselected length stroke multiple times, for example from 1 to 100 timesper rotation of the drive coupling 760. It should also be appreciatedthat while full and continuous rotation of the rotating coupling 760will usually be preferred, it would also be possible to rotationallyoscillate (periodically reverse the direction of rotation betweenclockwise and counter-clockwise) the rotating drive coupling 760, forexample to control a length of travel of the moveable active electrode725 in the window 726 where a rotation of less than 360° will result ina shortened length of travel. The stroke of the sliding actuator collar745 and electrode 725 can be between 0.01 mm and 10 mm, and in onevariation is between 0.10 mm and 5 mm. The selected RPM of the motordetermines the reciprocation rate, and in one variation a controller705C can select a motor operating RPM to provide a reciprocation ratebetween 1 Hz and 1,000 Hz, usually between 1 Hz and 500 Hz. In anothervariation, the RF ablation probe 700 can be selectively operated indifferent reciprocation modes (by controller 705C) to provide differentreciprocation rates to provide different RF effects when treatingtissue. In an additional variation, the length of the electrode strokecan be selected for different modes, wherein the housing 708 can beprovided with a slidable adjustment (not shown) to adjust the distancebetween the cam surfaces 747 and 762 of the sliding collar 745 androtating coupling 760, respectively.

The RF probe of FIGS. 18-22 also can be operated in different RF modes.As described above, a typical RF mode for dynamic RF ablationreciprocates the electrode 725 at a selected high speed while deliveringRF current in a cutting waveform to thereby create a plasma that ablatestissue. In another RF mode, the controller 705C can include an algorithmthat stops the reciprocation of electrode 725 in the extended positionof FIGS. 19A and 20A and then RF RF current in a coagulation waveformcan be delivered to the electrode 725. The operator can then move thestationary electrode over a targeted site for coagulation of tissue. Inyet another RF mode, the controller 705C can reciprocate the electrode725 as at slow rate (e.g., 1 Hz to 500 Hz) while delivering acoagulation waveform to coagulate tissue.

Referring to FIGS. 18, 21A-21B and 24, the rotating coupling 760 isrotationally maintained in hub 708 by a flange 770 that projects intoannular groove 772 in the hub 708. The rotating drive coupling 760 isconfigured for coupling with the drive shaft 775 and transverse pin 776of motor drive unit 105 as shown in FIG. 24. As in previous embodimentsof cutting or shaver assemblies, the negative pressure source 705B iscoupled to a passageway 778 in handpiece 702 (FIG. 23) that furthercommunicates through the interior of the handpiece with opening 780 inthe drive coupling 760 (see FIGS. 21A-21B) and lumen 782 in inner sleeve718 to suction tissue into window 726, as can be understood from FIGS.19A-21B.

FIG. 22 is a longitudinal sectional view of the device hub 708 rotated90° from the sectional views of FIGS. 21A-21B. FIG. 22 shows the meansprovided for connecting the RF source 705A to the probe 700 andelectrodes. In FIG. 23, first and second electrical leads 790 a and 790b are shown schematically extending from RF source 705A throughhandpiece 702 to electrical contact surfaces 792 a and 792 b in thereceiving channel 741 in the handpiece 702. FIG. 22 shows electricalcontacts 795 a and 795 b in hub 708 as described previously which engagethe contact surfaces 792 a and 792 b in the handpiece. In FIG. 22, thefirst electrical lead 790 a and contact surface 792 a delivers RFelectrical current to contact 795 a in hub 708 which provides at leastone ball and spring contact assembly 796 to deliver current to theconductive actuator collar 745 and inner sleeve 718 which is connectedto active electrode 725 as described above. It can be understood thatthe ball and spring contact assembly 796 will allow the actuator collar745 to reciprocate while engaging the contact assembly 796. In onevariation, two ball and spring contact assemblies 796 are provided onopposing sides of the hub 708 for assuring RF current delivery to theactuator collar 745. The inward portions of the two ball and springcontact assemblies 796 also are disposed in axial channels or slots 798a and 798 b in the actuator collar 745 and thus function as a slot andkey features to allow the actuator collar 745 to reciprocate but notrotate.

Referring again to FIG. 22, the second electrical lead 790 b connects tocontact surface 792 b in handpiece receiving channel 741 which engagesthe electrical contact 795 b in hub 708 of the RF probe 700. It can beseen that an electrical path 802 extends from electrical contact 795 bin the hub 708 to outer sleeve 716 wherein and an exposed portion of theouter sleeve 716 comprises a return electrode 815 as shown in FIGS. 18,19A-19B and 24. It should be appreciated that the outer sleeve 716 canbe covered on the inside and outside with a thin electrically insulatingcover or coating (not shown) except for the exposed portion whichcomprises the return electrode 815. The inner sleeve 718 has aninsulative exterior layer 820 such as a heat shrink polymer shown inFIGS. 19A-19B and 20A-20B. The insulative exterior layer 820 on theinner sleeve 718 is provided to electrically insulate the inner sleeve718 from the outer sleeve 716.

In a method of operation, it can be understood that the device can beintroduced into a patient's joint that is distended with saline solutiontogether with an endoscope for viewing the working space. Underendoscopic vision, the device working end is oriented to place theelectrode 725 against a targeted tissue surface in the patient's joint,and thereafter the RF source 705A and negative pressure source 705B canbe actuated contemporaneously to thereby suction tissue into the window726 at the same time that an RF plasma is formed about the reciprocatingelectrode 725 which then ablates tissue. The ablated tissue debris issuctioned through the windows 726 and 736 into lumen 782 of inner sleeve718 to the fluid outflow pathway in the handpiece 702. Ultimately, thetissue debris is carried though the outflow pump system to thecollection reservoir 830 (FIG. 23). The device and system can beactuated by the footswitch 707 a or a button 707 b in the control panelof the handpiece 702 as described previously.

FIG. 24 shows the RF ablation probe or assembly 700 from a differentangle where it can be seen that the rotating drive coupling 760 has abore 822 and at least one slot 824 therein to receive that motor driveshaft 775 and transverse pin 776. In another aspect of the invention,the drive coupling 760 has a smooth exterior surface 825 in 360° aroundthe coupling to provide an enclosure that surrounds and enclosed shaft775 and transverse pin 776. The exterior surface 825 and 360° enclosureis configured to prevent a fluid outflow indicated by arrow 832 (whichcarries resected tissue debris) from clogging the system. It can beunderstood that resected tissue may include elongated, sinewy tissuestrips that can wrap around the drive coupling 760 which is spinning at5,000-15,000 RPM after being suctioned with fluid through opening 780 inthe drive coupling 760. Prior art devices typically have a drive shaftand pin arrangement that is exposed which then is susceptible to“catching” tissue debris that may wrap around the coupling andeventually clog the flow pathway. For this reason, the rotating drivecoupling 760 has a continuous, smooth exterior surface 825. In an aspectof the present invention, a disposable arthroscopic cutting or ablationdevice is provided that includes a rotating drive coupling that isadapted to couple to a motor drive shaft in a handpiece, wherein therotating drive coupling has a continuous 360° enclosing surface thatencloses the drive shaft and shaft-engaging features of the drivecoupling. In other words, the drive coupling 760 of the invention hasmotor shaft-engaging features that are within an interior receivingchannel of the drive coupling. In another aspect of the invention,referring to FIG. 24, the drive collar 760 of a shaver blade includesenclosing features 838 a and 838 b that are configured to carry magnets840 a and 840 b. Such magnets are adapted to cooperate with at least oneHall sensor 845 in the handpiece 702. The at least one Hall sensor 845can be used for multiple purposes, including (i) calculating shaft RPM,(ii) stopping shaft rotation and thus electrode 725 and the inner sleevewindow 736 in a selected axial position, and (iii) identifying the typeof shaver blade out of a catalog of different shaver blades wherein thecontroller 704 that operates the RF source 705A, negative pressuresource 705B and motor controller 705C then can select differentoperating parameters for different shaver blades based on identifyingthe blade type.

FIGS. 25-28 illustrate another electrosurgical RF ablation assembly orprobe 1000 that is adapted for use with the handle or handpiece 702 andmotor drive unit 105 of FIG. 23. In this variation, the motor drive 105again does not rotate a cutting blade but is configured only for movinga hook shape electrode 1005 (FIG. 25) between a first non-extendedposition and a second extended position as can be seen in FIGS. 26A and26B.

As can be seen in FIG. 25, the RF probe 1000 again has a proximalhousing or hub 1006 that is coupled to an elongated extension portion orshaft 1010 with an outer diameter ranging from about 2 mm to 7 mm, andin one variation is 3 mm to 5 mm in diameter. The shaft 1010 extendsabout longitudinal axis 1012 to a working end 1015 that includes aceramic or other dielectric tip or body 1018 which can be a ceramic orglass material as described above. Referring to FIGS. 25 and 27, it canbe understood that the elongated shaft 1010 includes a thin wall sleeve1020 having an interior channel or lumen 121 therein and is fabricatedof a conductive material such as stainless steel. An optional insulatorlayer 1022 is disposed around a proximal and medial portion of thesleeve 1020. The ceramic tip or body 1018 is coupled to the distal endof sleeve 1020 by adhesives or other suitable means. In a variation, asshown in FIGS. 26A and 26B, the ceramic body 1018 has a distal surface1024 the defines a distal plane DP that is flat and orthogonal to thesleeve 1020, i.e., the axis 1012 of the sleeve is angled at 90° relativeto plane DP. In another variation, the distal surface 1024 and distalplane DP can be sloped or inclined at an angle between 45° to 90°relative to the axis 1012. Alternatively, such a distal surface can becurved in a concave or convex shape, or in other cases could havecombinations of planar and curved segments.

Referring to FIGS. 26A-26B and 27, the moveable hook electrode 1005extends through opening 1025 in a distal face 1026 of the dielectric tip1018. An electrode shaft 1028 that extends entirely through sleeve 1020which is connected to proximal drive mechanism 1030 (FIG. 25) in theinterior of hub 1006 for moving the electrode 1005 between thenon-extended position of FIG. 26A and the extended position of FIG. 26B.In the fully extended position of electrode 1005 shown is FIG. 26B, thesurface of the hook portion of the electrode can extend from 0.05″ to0.50″ from the distal surface 1024 of the dielectric tip 1018. As can beseen in FIGS. 26A-26B, the dielectric tip 1018 has a recess 1030 in itsdistal surface and a notch 1033 to receive the transverse portion 1035of the electrode 1005 when in the non-extended position of FIG. 26A.Thus, in the configuration shown in FIG. 26A, the distalmost surface ofthe working end 1015 comprises only the rounded edge 1036 of thedielectric member 1018 which is suited for introduction through anaccess incision or an introducer sleeve into a treatment site.

In this variation, the drive mechanism that moves the electrode 1005axially can be the same mechanism as described above in the previousembodiment and shown in FIGS. 21A, 21B and 22. That is, the motor drive105 in the handpiece 702 detachably couples to a drive coupling 1032 inthe hub 1006 and the motor's rotation is converted to linear motion asdescribed previously (FIG. 25). In FIGS. 26A, 26B and 27, it can be seenthat interior channel or lumen 121 in sleeve 120 is connected to thenegative pressure source 705B for aspirating fluid and tissue debrisfrom a treatment site. FIGS. 21A-22 illustrate the proximal end 1038 ofthe elongated member 1028 (phantom view) that carries hook electrode1005 can be coupled to an shortened inner sleeve 718 to allow for fluidoutflows indicated at arrows AR through the hub 708.

In the variation shown in FIGS. 26A-26B, the controller 704 (FIG. 23)includes control algorithms that slow down the motor speed and can beadapted to only move the electrode between the non-extended electrodeposition (FIG. 26A) and the extended electrode position (FIG. 26B). Thecontroller can use the Hall sensor signals as described above toindicate the rotational position of the drive coupling 1032 (FIG. 25),that again carries magnets 840 a and 840 b wherein control algorithmscan determine or confirm the linear position of the electrode 1005. AHall sensor 845 is shown in FIG. 23 that is proximate the magnets 840 aand 840 b. A joystick or button 707 b on the handpiece 702 (FIG. 23) canbe actuated by the physician to move the electrode 1005 between thenon-extended and extended electrode positions (FIGS. 26A-26B).

Referring to FIG. 27, it can be seen that the electrode 1005 cancomprise a tungsten wire or other similar material, and in onevariation, the electrode is a tungsten wire with a diameter of 0.020″,although other diameters are suitable depending on the overalldimensions of the device. As can be seen in FIG. 27, the elongatedmember or electrode shaft portion 1028 comprises a conductive hypotube1040 with the longitudinal portion 1042 of the electrode 1005 extendinginto and fixed in the lumen 1044 of hypotube 1040, which is onevariation can be a 0.032″ OD stainless steel hypotube. The longitudinalportion 1042 of electrode 1005 can be fixed to the hypotube 1040 bycrimping, welding, press fitting or other suitable means. FIG. 27further shows an insulator layer 1045 around the hypotube 1040 which canbe a heat-shrink sleeve which is used to electrically insulate thehytotube 1040 (which carries RF current to active electrode 1005) fromthe outer sleeve 1020 which comprises a return electrode 1050.

In another aspect of the invention, the dielectric distal tip 1018includes at least one fluid flow passageway therethrough that cancomprise the opening 1025 in distal face 1026 which receives thetranslatable electrode 1005. Such a flow passageway communicates withthe negative pressure source 705B (i.e., outflow pump) for removingfluid and tissue debris from a treatment site. In the variation of FIGS.26A-27, such a flow passageway includes a plurality of channel portions1055 a-1055 d projecting radially outwardly from opening 1025 throughwhich the electrode 1005 extends. FIGS. 29-30 illustrate otherdielectric tips 1018′ and 1018″ with other configurations of flowchannels 1060A and 1060B that may be used. The electrode shaft mayextend through opening 1025 in the center of the dielectric tip 1018 orany off-center position.

Still referring to FIGS. 26A-27, the distal tip 1018 and flow channels1055 a-1055 d have certain characteristics and features to performoptimally for removing fluids and tissue debris from a treatment site.In one aspect, the flow channels 1055 a-1005 d are provided with asufficient cross-section to allow for fluid flows of at least 50 ml/min,and more often at least 100 ml/min or at least 200 ml/min. As areference, the negative pressure source or outflow pump 705B used in onevariation of the invention is capable of fluid outflows of 1,250 ml/minwhen there are no restrictions to such fluid outflows.

In order to accommodate the fluid outflows described above, the totalcross-sectional area of the flow channels 1055-1055 d in the variationshown in FIGS. 26A-27 indicated at CA is least 0.001 square inches andoften greater than 0.002 square inches.

In another aspect, referring to FIGS. 27 and 28, the distal tip 1018 isconfigured with a plurality of longitudinal elements 1065 intermediatethe flow channels 1055 a-1055 d that support the electrode'slongitudinal portion 1042. The sectional view of FIG. 28 shows thedielectric tip 1018 without the electrode to better view thelongitudinal elements 1065. As shown in FIG. 28, the elements 1065 onlycontact the electrode longitudinal portion 1042 at a single point orover a short longitudinal dimension Z, for example, less than 2 mm orless than 1 mm. In another aspect, the channels 1055 a-1055 d transitionfrom the first distal cross-sectional area described above to channels1075 that have a much larger cross-sectional area in the proximaldirection as shown in FIGS. 27 and 28. It has been found that tissuedebris can get entangled in elongate flow channels, therefore it isuseful to provide such flow channels 1055 a-1055 d with a cross-sectionthat increases to larger channels 1075 in the proximal direction, thatis, in the direction of fluid outflow indicated by arrows AR in FIG. 27.

FIG. 28 is a slightly off-center sectional view of the dielectric tip1018 without showing the electrode 1005. It can be seen that thecross-sectional area of the channels 1055 a-1055 d increase in theproximal direction from channel area CA in opening 1025 to channel areaCA′ in the proximal portion 1077 of the dielectric tip 1018, ignoringthe area of the electrode 1005 or shaft 1028. In the variation shown inFIG. 28, it can be seen that more proximal longitudinal rails orfeatures 1080 are dimensioned to support the hypotube 1040 that carriesthe electrode 1005 as described above.

In a method of use, the single-use probe 1000 of FIGS. 25-26B isassembled with handpiece 702 and the default position of the electrode1005 is the non-extended or retracted position of FIG. 267A. Afterassembling the disposable probe 1000 and handpiece, the controller 704and control algorithms therein can recognize the type of probe, whichcan be accomplished with Hall sensors that recognize the strength one ormore magnets 1072 in hub 708 as shown in the probe variation of FIG. 22.It can be understood that a magnet 1072 in FIG. 22 could be providedwith from 2 to 10 different strengths that can be distinguished by aHall sensor 1075 (FIG. 22), then a corresponding 2 to 10 different probetypes can be identified. If two magnets are disposed on opposing sidesof the hub 708 as shown in FIG. 22, each having from 2 to 10 differentstrengths, then the large number of permutations would allow foridentification of a larger number of probe types. It should also beappreciated that the rotating magnets 840 a and 840 b in the drivecoupling 760 of FIG. 24 can have different strengths in different probetypes and then can be used for acquiring Hall sensor signals for (i)rotating operating parameters as well as being used for (ii) devicerecognition or probe type identification. The controller 704 isconfigured with a control algorithm to activate and de-activate themotor drive unit to thereby stop movement of the elongate member orshaft 1028 and electrode 1005 in both the non-extended position (FIG.26A) and the extended position (FIG. 26B). In one variation, the controlalgorithm is further configured to deliver RF current to the electrode1005 only in the electrode-extended position of FIG. 26B. The systemfurther is configured to selectively deliver RF current to the electrodein a cutting waveform or a coagulation waveform.

In a method of use, after the probe 1000 has been recognized andidentified, the controller optionally can be configured to actuate themotor drive unit 105 to then move and stop electrode 1005 in thenon-extended position of FIG. 26A. Thereafter, the physician canintroduce the working end 1015 through an incision into a treatment sitein a patient's joint. The physician then can use control button 707 b onthe handpiece 702 to actuate the motor drive 105 which moves and stopsthe electrode 1005 in the extended position as shown in FIG. 26B.Thereafter, the physician can engage targeted tissue with the hookelectrode 1005 and activate RF energy delivery with either an actuatorbutton 707 b on the handpiece 702 or a foot pedal 770 a (FIG. 23). Thecontroller 704 can be configured to activate the negative pressuresource 705B contemporaneous with the activation of RF delivery.Alternatively, the negative pressure source 705B can be operating at afirst aspiration level as the physician prepares to use RF, and then asecond increase aspiration level when the RF is activated. Then, withthe RF activated, the physician can move or translate the electrode 1005to cut and ablate tissue. When the treatment is completed, the physicianthen can use an actuator button or joystick to move the electrode to thenon-extended position of FIG. 26A and withdraw the probe 1000 from thetreatment site.

The method of using probe 100 as described above contemplates thatelectrode 1000 being static in the extended position shown in FIG. 26Bwith the physician manually translating the hook electrode 1005 againsttargeted tissue, for example, to cut a ligament. In another method ofuse, herein called a “dynamic ablation mode”, the controller 704 can beprovided with control algorithms that rotate the motor drive 105 torapidly reciprocate the wire electrode 1005 during RF energy delivery tothe electrode. It has been found that such a rapid reciprocation of theelectrode 1005 over a relatively short stroke can facilitate RF cuttingof tissue, which is similar to the RF cutting effect with the probevariations of FIGS. 18-22 above. In one variation, the stroke ofelectrode 1005 in the dynamic ablation mode can range from 0.01 mm and 5mm, often being in a range between 0.1 mm and 4 mm. The rate ofreciprocation can range from 5 Hz to 500 Hz, and often in the range from10 Hz to 100 Hz.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

Other variations are within the spirit of the present invention. Thus,while the invention is susceptible to various modifications andalternative constructions, certain illustrated embodiments thereof areshown in the drawings and have been described above in detail. It shouldbe understood, however, that there is no intention to limit theinvention to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructions,and equivalents falling within the spirit and scope of the invention, asdefined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

What is claimed is:
 1. An electrosurgical probe for use with a handpiecehaving a motor drive unit and an RF current contact, said probecomprising: an elongate shaft having a longitudinal axis, a distaldielectric tip, and a proximal hub configured to be detachably securedto the handpiece; a hook electrode reciprocatably mounted in the distaldielectric tip; an RF connector on the hub configured to couple to theRF current contact in the handpiece when the hub is secured to thehandpiece; and a drive mechanism in the hub mechanically coupled to thehook electrode, wherein the drive mechanism is configured to engage arotational component of the motor drive unit when the hub is secured tothe handpiece and wherein the drive mechanism converts rotational motionfrom the rotational component into axial reciprocation and transmits theaxial reciprocation to the hook electrode to axially shift the hookelectrode between a non-extended position and an extended positionrelative to the dielectric tip.
 2. The electrosurgical probe of claim 1wherein the drive mechanism comprises an elongate member disposed in theelongate shaft and having a distal end attached to the hook electrode.3. The electrosurgical probe of claim 2 wherein the drive mechanismfurther comprises a rotatable a cam assembly located in the hub toreceive rotational motion from the rotational component of the motordrive unit and covert the rotational motion into axial reciprocationwhich is delivered to the elongate member.
 4. The electrosurgical probeof claim 2 wherein the elongate member is electrically conductive andconnected to deliver RF current from the RF connector on the hub to hookelectrode.
 5. The electrosurgical probe of claim 4 wherein a proximalportion of the elongate member extends through a central opening in thehub and an intermediate portion of the elongate member extends through acentral lumen in the shaft, wherein the hook electrode is reciprocatablydisposed in an opening in the dielectric tip.
 6. The electrosurgicalprobe of claim 5 wherein the central lumen in the shaft is configured tobe connected to a negative pressure source.
 7. The electrosurgical probeof claim 6 wherein the hub is configured to connect the central lumen tothe negative pressure source.
 8. The electrosurgical probe of claim 1,wherein the shaft comprises an outer tube having a longitudinal lumenand an inner member reciprocatably received in the longitudinal lumen ofthe outer tube.
 9. The electrosurgical probe of claim 8 wherein thedielectric tip is attached to a distal end of the outer tube and has anopening which communicates with the longitudinal lumen of the outer tubewhich is configured to be connected to a negative pressure source. 10.The electrosurgical probe of claim 9 wherein the hook electrode extendsfrom a distal end of the inner member.
 11. The electrosurgical probe ofclaim 9 wherein the inner member comprises a rod and the hook electrodecomprises a bent wire attached to a distal end of the rod.
 12. Theelectrosurgical probe of claim 11 wherein a distal face of the distaltip has a notch and wherein a lateral end of the bent wire of the hookelectrode is configured to be retracted into the notch when the hookelectrode is in its non-extended position.
 13. The electrosurgical probeof claim 1 wherein the dielectric tip has at least one flow channelcommunicating with at least one interior channel in the shaft, saidinterior channel being configured to be connected to a negative pressuresource.
 14. The electrosurgical probe of claim 13 wherein the at leastone flow channel has a cross-sectional area of at least 0.001 squareinch.
 15. The electrosurgical probe of claim 14 wherein thecross-sectional area of said at least one flow channel is configured toaccommodate fluid outflows of at least 50 ml/min when said at least oneinterior channel and said at least one flow channel are connected to thenegative pressure source.
 16. The electrosurgical probe of claim 13wherein said at least one flow channel comprises a portion of an openingin the dielectric tip which receives the hook electrode.
 17. Theelectrosurgical probe of claim 13 wherein the 1 dielectric tip has atleast one opening to receive the hook electrode in addition to the atleast one flow channel.
 18. The electrosurgical probe of claim 13wherein the dielectric tip includes at least one opening to receive thehook electrode.
 19. The electrosurgical probe of claim 18 wherein the atleast one opening which receives the hook electrode is shaped with (i) aplurality of support elements adapted to support an elongate memberwhich supports the hook electrode and (ii) a plurality of flow channelsadapted to provide fluid flow in response to suction from the negativepressure source.
 20. The electrosurgical probe of claim 19 comprising atleast three support elements.
 21. The electrosurgical probe of claim 1wherein the dielectric tip comprises a ceramic material.
 22. Anelectrosurgical system comprising: the electrosurgical probe of claim 1;and a handpiece configured to be detachably connected to the hub on theelectrosurgical probe, wherein the handpiece includes a motor drive unitconfigured to mechanically couple to the drive mechanism in theelectrosurgical probe for longitudinally reciprocating the elongatemember and hook electrode between the non-extended position and theextended position when the hub is secured to the handpiece.
 23. Theelectrosurgical system of claim 22 further comprising a controllerconfigured to activate and de-activate the motor drive unit to shift theelongate member and hook electrode between the non-extended position andthe extended position relative to the dielectric tip.
 24. Theelectrosurgical system of claim 23 wherein the controller is configuredto deliver RF current to the electrode only in the extended position.25. The electrosurgical system of claim 24 wherein the RF current has awaveform is selected from a group of waveforms consisting of a cuttingwaveform and a coagulation waveform.
 26. The electrosurgical system ofclaim 24 wherein the controller is configured to longitudinallyreciprocate the elongate member and hook electrode.
 27. Theelectrosurgical system of claim 23 wherein the controller is configuredto simultaneously reciprocate the hook electrode and deliver RF currentto the hook electrode.
 28. The electrosurgical system of claim 22wherein the drive mechanism, motor drive unit, and the controller areconfigured to reciprocate the hook electrode over a distance between0.01 mm and 5 mm, or between 0.1 mm and 4 mm.
 29. The electrosurgicalsystem of claim 22 wherein the controller and the motor drive unit areconfigured to reciprocate the hook electrode at a rate in a range from 5Hz to 500 Hz, or in a range from 10 Hz to 100 Hz.
 30. A method forassembling an electrosurgical probe system, said method comprising:providing a first electrosurgical probe as in claim 1; providing ahandpiece including a motor drive unit and an RF current contact; andremovably attaching the hub on the first electrosurgical probe to thehandpiece, wherein such attachment mechanically couples the motor driveunit in the handpiece to the drive mechanism in the electrosurgicalprobe for longitudinally reciprocating an elongate member in the probeto reciprocate an RF electrode between the non-extended position and theextended position.
 31. A method as in claim 30, wherein removablyattaching the hub on the electrosurgical probe to the handpiece alsocouples an RF connector on the hub to the RF current contact on thehandpiece.
 32. A methods as in claim 31, further comprising detachingthe first electrosurgical probe from the handpiece after theelectrosurgical probe system has been used to treat a patient.
 33. Amethod as in claim 32, further comprising removably attaching the hub ona second different probe to the handpiece and treating the patient withthe probe.
 34. A method for electrosurgically resecting tissue, saidmethod comprising: positioning a distal end of a shaft having alongitudinal axis at a tissue target site so that a distal tip of theshaft is adjacent a target tissue; rotating a motor in a handpieceattached to a proximal end of the shaft to axially reciprocate a hookelectrode at the distal tip of the shaft between an axially non-extendedposition and an extended position relative to the dielectric tip;engaging the hook electrode against target tissue; and deliveringelectrical current through the hook electrode to the target tissueengaged by the electrode.
 35. The method of claim 34, wherein the motoris rotating so that the hook electrode is reciprocating when the hookelectrode is engaged against the target tissue.
 36. The method of claim34, wherein the motor is stopped so that the hook electrode isstationary when the hook electrode is engaged against the target tissue.37. The method of claim 34, further comprising drawing a negativepressure through a central lumen of the shaft to aspirate a regionsurrounding the target tissue when the hook electrode is engaged againstthe target tissue.
 38. The method of claim 37 wherein the distal end ofthe shaft is submerged in a conductive fluid when the distal tip of theshaft is engaged against the target tissue.
 39. The method of claim 38wherein the current is radiofrequency current delivered to cauterize orablate the target tissue.